Harmonic-based wireless pressure sensor and wireless power transfer system for implantable wireless sensor networks
Abstract
An implantable wireless sensor network is a key technology to enable smart healthcare in the future. As the sensor network might include multiple implanted devices for functions such as disease-monitoring and rehabilitation, miniature implementation of the devices and effective wireless power transfer to the devices will be important issues for the implantable wireless sensor network. In this dissertation, a passive harmonic-based pressure sensor implanted inside a mouse eye is presented as a representative example of smallest implantable devices for which power budget is not enough to turn on active devices. Methods to fabricate a MEMS capacitive pressure sensor on a biocompatible and flexible polymer substrate are presented. Then, a MEMS pressure sensor is integrated with a diode and a Nitinol antenna on a Parylene substrate to implement a harmonic-based implantable pressure sensor. A pressure sensing exploiting the harmonic-based IOP sensor implanted inside a mouse eye shows that the compatibility of the polymer-based ultra-miniature sensor with implantation. However, more accurate monitoring using active implanted devices is required for most of biomedical applications. Therefore, as a feasible solution for effective wireless power transfer to active implanted components, a mixed system of RF and inductive magnetic resonance coupling (MRC) using diode-generated harmonic is proposed. In the system, the design methodologies of the MRC based on bandpass filter (BPF) synthesis enables effective power transfer to the complex impedance of a rectifier, compensation for the efficiency drop by tolerance in placement of coils, and effective power distribution to multiple implanted devices. Additionally, an interface module using harmonic generated by a diode enables the integration of the RF radiation and the magnetic resonance coupling (MRC). The system is useful for a possible application such as neural interface in brain. Finally, polymer-based 3D packaging techniques can be utilized for miniature implementation of the proposed system in an implantable. If the techniques explored in this thesis are tied together, a selective power transfer system for more effective power transfer and the implementation of power transfer system in an implantable size will be feasible.
Degree
Ph.D.
Advisors
Chappell, Purdue University.
Subject Area
Electrical engineering
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.